The removal of chemical oxygen demand (COD) and turbidity from cardboard paper mill effluents was experimentally investigated using aluminum and iron electrodes followed by adsorption of treated wastewater on granular activated carbon (GAC). The effects of electrolyse time, current density, initial pH, adsorption time, stirring, and granular activated carbon (GAC) amount were studied. For electrolyses, the maximum removal efficiencies of COD and turbidity under optimal operating conditions i.e. pH = 5.29 for Al electrode and pH = 7.21 for Fe electrode, with a current density of 4.41 mA/cm2 and operating time of 10 min were 75.37% and 99.93% for Al electrode and 78.76% and 99.92% for Fe electrode, respectively. For electrocoagulation (EC) and adsorption process under operating conditions i.e. pH = 3.21 at 300 rpm with contact time of 120 min for Al electrode and 180 min for Fe electrode, the maximum removal efficiencies of COD were 98.97% and 93.37%, respectively. The results obtained show good adsorption efficiency and short contact time obtained after Al‐EC due to interference from color of dissolved iron. The present study proves the effectiveness of electrocoagulation/adsorption process for the highly concentrated organic pollutants present in paper mill effluents. © 2011 American Institute of Chemical Engineers Environ Prog, 2011.
In this study, electrocoagulation of Marine Blue Erionyl MR (acid dye) and electrocoagulation followed by adsorption of Brilliant Blue Levafix E‐BRA (reactive dye) from aqueous solutions were investigated, using aluminum electrodes and granular activated carbon (GAC). In the electrocoagulation and adsorption of dyestuff solutions, the effects of current density, loading charge, pH, conductivity, stirring velocity, contact time, and GAC concentration were examined. The optimum conditions for the electrocoagulation process were identified as loading charges 7.46 and 1.49 F/m 3, for a maximum abatement of 200 mg/L reactive and acid dye, respectively. The residual reactive dye concentration was completely removed with 700 mg/L GAC. The results of this investigation provide important data for the development of a combined process to remove significant concentrations of recalcitrant dyes from water, using moderate activated carbon energy and aluminum consumption, and thereby lowering the cost of treatment.
Les effluents textiles contenant des colorants réactifs sont souvent très complexes et nécessitent des traitements intensifs. De nos jours, la combinaison de deux ou plusieurs techniques opératoires, en se servant des progrès scientifiques permettant une bonne commande du procédé, est devenue une alternative intéressante. Par ailleurs, les argiles et les minéraux argileux, du fait d’avoir des propriétés leur permettant d’être à la fois adsorbants et adjuvants de floculation, attirent un intérêt particulier des chercheurs dans le domaine du traitement des effluents industriels. Dans cette étude, un effluent textile qui représente les eaux résiduaires de l’unité de teinture du coton Denitex, Tlemcen en Algérie, a été traité par un procédé combiné. Le traitement comporte deux étapes : la première est une coagulation-floculation (CF) à l’aide des sels d’aluminium pré-neutralisés jusqu’à un rapport OH/Al égal à 2,25, donnant naissance au polycation de structure AlO4Al12(OH)24(H2O)12, appelé aussi Al13, en association avec une bentonite algérienne (B). Dans la deuxième étape, qui succède à la première, l’électroflottation (EF) a été utilisée pour exploiter son rôle de séparation solide-liquide, et aussi pour améliorer l’efficacité du traitement. Dans les deux techniques utilisées : (CF) et (EF), les conditions opératoires, telles que le pH, la concentration des réactifs, le temps de contact, d’une part, et aussi la densité du courant électrique et la consommation d’énergie, d’autre part, ont été déterminées. Les résultats obtenus indiquent que l’effluent traité par cette méthode ne contient pratiquement plus de couleur ni de DCO : 99,71 % et 99,07 % d’élimination sont obtenus, respectivement.Textile effluents containing reactive dyes are often very complex and require intensive treatments. Nowadays, the combination of two or more techniques has become an interesting alternative, because of scientific progress allowing for a good control of the processes. Clays and clay minerals, because of their properties enabling them to be simultaneous adsorbents and flocculation additives, are of particular interest to researchers in industrial wastewater treatment. In this study, a textile effluent that represents the wastewater of a cotton dyeing plant (Denitex, Tlemcen, Algeria) was treated by a combined process. The treatment was divided into two stages: the first was a coagulation-flocculation (CF) stage using pre-neutralized aluminium salts, called Al13 polycations (AlO4Al12(OH)24(H2O)12), as a coagulant associated with an Algerian bentonite (B); in the second stage, an electroflotation technique (EF) was used. The EF technique was not only used as a solid-liquid separation operation, but also in the improvement of the effectiveness of the treatment. For the CF and EF treatments of wastewater, the effects of pH, reagent concentrations, contact times as well as electric current and energy consumption were investigated. The effluent treated by this combined method contained essentially no colour or COD: 99.7% and 99.1% eliminat...
The present study aimed to assess the efficiency of two wastewater treatment plants (WWTPs) operating with different biological processes and to investigate the electrocoagulation process as alternative to improve their operation.Results revealed the consistent efficiency of urban WWTP that uses activated sludge process, the station operated with removal efficiencies higher than 91% for biological oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS) and produced high quality effluent whereas the efficiency of WWTP of an industrial complex using trickling filter process was in the monitored period very small and did not meet the minimum acceptable treatment efficiency of discharged wastewater. The treatment assays with electrocoagulation process using aluminium electrodes exhibited high COD removal particularly for plant of industrial site, the optimal operating conditions for the maximum COD removal are found to be the initial pH of 3, current density of 29.79 mA/cm 2 , electrolysis time of 5 min and charge loading of 26.11 F/m 3 . Under these conditions, the removal efficiency of COD is found to be 79% . Consequently, electrocoagulation process can be recommended to improve the performance of WWTPs. Nonetheless, the implementation of EC into industrial or municipal systems should be investigated more.
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